DENIERS SAY:

Ice melting on Mount Kilimanjaro has local causes. So why should we believe in global climate change?

SCIENCE SAYS:

It's not about one glacier or one mountain. Overall, glaciers are losing 150 billion tons of ice a year.

Mount Kilimanjaro is losing snow and ice. Is this because of global warming? Maybe, but changes in local weather patterns might be more important. Conditions have become drier, meaning less snow is falling to replenish the glaciers and reflect sunlight. Researchers have found that deforestation of the mountain’s foothills is a significant contributor to this drying trend. Still, as one researcher of Kilimanjaro’s deforestation put it: “The fact that the loss of ice on Mt. Kilimanjaro cannot be used as proof of global warming does not mean that the Earth is not warming. There is ample and conclusive evidence that Earth's average temperature has increased in the past 100 years, and the decline of mid- and high-latitude glaciers is a major piece of evidence."

Additional info from The Climate Reality Project

What’s behind this shrinkage? There are probably several factors at play. Think of a glacier as a bank account. Just as the balance in your bank account depends on how much money you put in and take out, the “balance” of a glacier over a given time period depends on the formation of new ice (via rain and snowfall) and the loss of old ice (mostly through melting).

Some scientists believe the retreat of Mount Kilimanjaro's glacier can be attributed in part to a reduction in snow caused by deforestation or land-use change. Cutting down forests allows winds to sweep up the mountain, which in turn can affect cloud formation, and therefore the amount of rainfall. But more research is required to assess the extent to which deforestation is affecting Mount Kilimanjaro's glacier.

Besides, less rain and snow is not incompatible with other causes of ice loss — like increased air temperatures caused by global warming. As one scientist put it, “Based on what is now known, it would be highly premature to conclude the retreat and imminent disappearance of the Kilimanjaro glaciers has nothing to do with warming of the air…”

But don't let the continuing Kilimanjaro investigation distract you from the bigger picture. Glaciers all over the world are shrinking, and global climate change is the main reason for this trend. A recent study found that mountain glaciers and polar ice sheets lost more than 530 gigatons of ice per year from 2003 to 2010, making a significant contribution to global sea level rise. We don't need to wait around until we solve the Kilimanjaro question before we act on climate change. In fact, we can't afford to wait.